Minimally invasive tissue prosthesis implanting device and method

ABSTRACT

A tissue prosthesis delivery device ( 10 ) includes an elongate, tubular introducer element ( 12 ), the element having a tissue piercing distal end ( 14 ) with an opening ( 16 ) arranged proximally of the distal end ( 14 ). A closure member ( 18 ) is associated with the introducer element ( 12 ) for opening and closing the opening ( 16 ) of the introducer element ( 12 ). An expansible prosthesis envelope ( 20 ) is received in a collapsed configuration within the tubular introducer element ( 12 ) to be deployed laterally of the introducer element ( 12 ) through the opening ( 16 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from U.S. Provisional Patent Application No. 60/866,836 filed on 21 Nov. 2006, the contents of which are incorporated herein by reference.

FIELD

This invention relates, generally, to implanting a tissue prosthesis, such as an intervertebral disc nucleus prosthesis, and, more particularly, to a tissue prosthesis delivery device and to a system for, and a method of, implanting a tissue prosthesis.

BACKGROUND

Various techniques have been proposed for dealing with age or injury related intervertebral disc degeneration. Two techniques in use are disc removal and fusion. Both of these techniques involve major invasive surgery with the related risks. More recently, another technique employed has involved the replacing of a degenerative disc with an artificial disc. This, once again, is carried out using major invasive techniques.

An intervertebral disc comprises two parts, an annulus fibrosis surrounding a nucleus pulposus. The intervertebral disc cooperates with end plates of the vertebrae between which it is sandwiched. Still more recently, techniques have been proposed to replace only the nucleus pulposus of the disc in circumstances where the degeneration is detected at a sufficiently early stage. Such techniques may be able to be performed in a minimally invasive manner.

A need exists generally when implanting a tissue prosthesis to cause as little trauma to the surrounding tissue as possible. For example, in the case of an intervertebral disc, one would aim, when doing minimally invasive replacement of a degenerative nucleus pulposus, to minimise trauma to the surrounding annulus fibrosis of the disc.

SUMMARY

According to a first aspect of the invention, there is provided a tissue prosthesis delivery device which includes

-   an elongate, tubular introducer element, the element having a tissue     piercing distal end with an opening arranged proximally of the     distal end; -   a closure member associated with the introducer element for opening     and closing the opening of the introducer element; and -   an expansible prosthesis envelope received in a collapsed     configuration within the tubular introducer element to be deployed     laterally of the introducer element through the opening.

The device may include a tissue removal mechanism carried in the introducer element to be extended through the opening to aid in tissue removal at a site in the patient's body where the prosthesis is to be implanted.

The tissue removal mechanism may include a filamentary element which is extended from the opening to effect tissue removal. The filamentary element may be extended in a bowed configuration from the opening. Tissue removal may then be effected by rotating the introducer element while the filamentary element is in its bowed configuration.

Further, the tissue removal mechanism may be conductive to be energised to effect tissue removal. More particularly, the tissue removal mechanism may be energised with RF energy to effect tissue removal.

The device may include a control member for controlling operation of the tissue removal mechanism. The control member may be removably mounted to a proximal end of the introducer element, the tissue removal mechanism being removable for allowing deployment of the prosthesis envelope.

The envelope may be an elastically deformable envelope. The envelope may be of an elastomeric material, more particularly, a silicone material.

The introducer element may be conductive to stimulate surrounding nerves in the patient's body electrically to evoke a response to reduce the likelihood of causing nerve damage as the introducer element is manoeuvred through the patient's body.

The closure member may be a sleeve displaceably arranged relative to the introducer element. The sleeve may be axially or rotatably displaceable relative to the sleeve. In the latter case, the sleeve may define a distal slot which is brought into register with the opening when the sleeve is rotated relative to the introducer element.

The device may include a filler tube in the introducer element with the envelope being mounted on a distal end of the filler tube and a proximal end of the filler tube being connectable to a supply of filler material.

Further, the device may include a connection to a withdrawal device for withdrawing fluid from the envelope.

According to a second aspect of the invention, there is provided a tissue prosthesis delivery device which includes

-   an elongate, tubular introducer element, the element having a tissue     piercing distal end with an opening arranged proximally of the     distal end; -   a closure member associated with the introducer element for opening     and closing the opening of the introducer element; and -   a tissue removal mechanism carried in the introducer element to be     extended through the opening to aid in tissue removal at a site in     the patient's body where the prosthesis is to be implanted.

According to a third aspect of the invention, there is provided a tissue prosthesis delivery device which includes

-   an elongate, tubular introducer element, the element having a tissue     piercing distal end with an opening arranged proximally of the     distal end; -   a closure member associated with the introducer element for opening     and closing the opening of the introducer element; and -   at least the distal end of the introducer element being conductive     to stimulate surrounding nerves in the patient's body electrically     to evoke a response to reduce the likelihood of causing nerve damage     as the introducer element is manoeuvred through the patient's body.

The invention extends also to a system for implanting a tissue prosthesis, the system including

-   a tissue prosthesis delivery device as described above; -   a sensor pack attachable to the patient's body for sensing a     response from any stimulated nerves; and -   an enunciator for alerting a clinician to a stimulated nerve.

The sensor pack may include a plurality of sensors, each of which is attachable at a predetermined location on the patient's body.

The enunciator may include an electromyograph (EMG).

According to a fourth aspect of the invention, there is provided a method of implanting a tissue prosthesis, the method comprising

-   minimally invasively introducing an introducer element into a     patient's body using a tissue piercing distal end of the introducer     element and the introducer element being tubular and carrying an     expansible prosthesis envelope in a collapsed state within the     introducer element proximally of the distal end; -   at a site in the patient's body at which the prosthesis is to be     formed, deploying the envelope through an opening defined,     proximally of the distal end, in a side wall of the introducer     element by charging a filler material into an interior of the     envelope to cause the envelope to expand and conform to a cavity at     the site in the patient's body; and -   detaching the expanded envelope from the introducer element and     withdrawing the introducer element.

The method may include energising at least the distal end of the introducer element to evoke a response from surrounding nerves of the patient as the introducer is manoeuvred to the site to inhibit damage to the nerves.

The method may include, initially, removing tissue from the site using the introducer element. The introducer element may include a tissue removal mechanism and the method may include extending the tissue removal mechanism through the opening of the introducer element and manipulating the introducer element to facilitate removal of tissue from the site by the tissue removal mechanism. Further, the method may include energising the tissue removal mechanism with RF energy to aid in tissue removal.

The method may include, after tissue removal has been completed, removing the tissue removal mechanism from the introducer element to allow the prosthesis envelope to be expanded through the opening of the introducer element.

The opening may be closed by a closure member and the method may include displacing the closure element relative to the introducer element when the introducer element is in the desired position relative to the site to place the interior of the introducer element in communication with the site.

The method may include expanding the envelope to a size greater than a cavity which the envelope is to fill so that, upon removal of the introducer element after filling of the envelope, the envelope conforms to the size of the cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a three dimensional view of an embodiment of a tissue prosthesis delivery device;

FIG. 2 shows a schematic sectional side view of the delivery device, in use;

FIG. 3 shows a three dimensional view of a distal portion of the delivery device with its opening open;

FIG. 4 shows a plan view of a distal portion of the delivery device with its opening open;

FIG. 5 shows a control member of the delivery device in a first position;

FIG. 6 shows the control member in a second position;

FIG. 7 shows a three dimensional view of the distal portion of the delivery device with a tissue removal mechanism in an extended, operative position;

FIG. 8 shows a schematic sectional side view of the distal portion of the delivery device in situ with the tissue removal mechanism in its extended, operative position;

FIG. 9 shows a three dimensional view of the delivery device with a tissue prosthesis envelope expanded and ready to be released from the delivery device; and

FIG. 10 shows a schematic representation of an embodiment of a system for implanting a tissue prosthesis.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT

In the drawings, reference numeral 10 generally designates an embodiment of a tissue prosthesis delivery device. The device 10 includes an elongate tubular introducer element 12. The element 12 has a tissue piercing distal end in the form of a pointed tip 14 with an opening 16 (shown more clearly in FIGS. 3, 4 and 7 of the drawings), arranged proximally of the tip 14.

A closure member 18 is associated with the introducer element 12 for openably closing the opening 16 of the introducer element 12.

An expansible prosthesis envelope 20 is received in a collapsed configuration in the introducer element 12 to be deployed laterally of the introducer element 12 through the opening 16, as will be described in greater detail below.

The delivery device 10 is intended particularly for use in intervertebral disc nucleus replacement. It will, however, be appreciated that the delivery device 10 could be used in other applications. However, for ease of explanation, the delivery device 10 will be described with reference to its application to intervertebral disc nucleus replacement.

The intervertebral disc is shown schematically at 22 in FIGS. 2 and 8 of the drawings. The disc 22 includes an annulus fibrosis, or annulus 24. The annulus 24 is sandwiched between end plates 26 of adjacent vertebrae. The annulus 24 and the end plates 26 define a cavity 28 in which a nucleus 30 is contained. Generally, with a diseased intervertebral disc 22, the nucleus 30 degenerates and leaks through the annulus 24. Thus, for replacement of the nucleus 30, it may, in certain circumstances, not be necessary to remove nuclear tissue from within the disc 22.

The delivery device 10 includes a tissue removal mechanism in the form of a nucleotomy wire 32. The nucleotomy wire 32 is mounted longitudinally in the tubular element 12 and can be extended out of the opening 16. The nucleotomy wire 32 overlies the tissue prosthesis envelope 20 when the tissue prosthesis envelope 20 is in its collapsed configuration. The nucleotomy wire 32 is controlled by a control member 34 (FIG. 1). The control member 34 cooperates with a boss 36 arranged at a proximal end of the introducer element 12.

As shown more clearly in FIGS. 5 and 6 of the drawings, when the nucleotomy wire 32 is in a retracted configuration, as shown in FIGS. 2 to 4 of the drawings, the control member 34 is in an extended position relative to the boss 36. The control member 34 has a threaded shank (FIG. 5). By screwing the control member 34 into the boss 36, the nucleotomy wire 32 is urged out of the opening 16 into a bowed configuration as shown in FIG. 7 of the drawings. In this configuration, when the distal part of the delivery device 10 is within the cavity 28 of the disc 22, by rotating the introducer element 12 about its longitudinal axis, as shown by arrow 40 (FIG. 7), as well as by moving it longitudinally to and fro nuclear material can be removed. In this regard, it is to be noted that, if desired, the nucleotomy wire 32 can be fabricated to be conductive. Thus, the nucleotomy wire 32 can, additionally, be energised with RF energy to aid in removal of nuclear material from within the cavity 28 of the disc 22.

As shown in FIG. 8 of the drawings, a distal end 32.1 of the nucleotomy wire 32 is fixed in position within the tip 14 of the introducer element 12. Further, the tip 32.1 of the nucleotomy wire 32 is shaped to encourage bowing of the nucleotomy wire 32 when the control member 34 is screwed into the boss 36.

The nucleotomy wire 32 is able to be removed from the introducer element 12 by unscrewing the control member 34 from the boss 36 completely and withdrawing it.

A lumen 41 (FIG. 8) of the introducer element 12 functions as an evacuation tube so that, when nuclear material is dislodged by the nucleotomy wire 32, it can be withdrawn from the cavity 28 of the disc 22 through the opening of the 16 of the introducer element 12 by suction.

As shown more clearly in FIG. 8 of the drawings, the nucleotomy wire 32 is mounted distally of a filler tube 42 which extends through the introducer element 12. A proximal end of the filler tube 42 is connected, in use, to a source of filler material (not shown). The filler tube 42 is, optionally, of a flexible material to render it collapsible.

Once the nucleotomy wire 32 has been removed from the introducer element 12, the envelope 20 can be expanded by charging filler material into the envelope 20 to form a nuclear prosthesis 44 (FIG. 9).

The tip 14 of the introducer element 12 of the device 10 is a conductive tip 14. The tip 14 is, in use, energised when the introducer element 12 is inserted into the patient's body so that the tip 14 stimulates surrounding nerves and evokes a response from the nerves.

In FIG. 10 of the drawings, reference numeral 50 generally designates an embodiment of a system for inserting a tissue prosthesis. The system 50 includes the delivery device 10. The system 50 further includes a sensor pack 52 comprising a plurality of sensors 54. Typically, four such sensors 54 are provided which are attached at various locations on a patient's body and which pick up muscle contractions arising from stimulation of nerves. These sensors 54 are associated with the muscles stimulated by nerves radiating from the spinal cord in the lumbar region of the spine and are typically in the legs of the patient. Thus, the sensors 54 are attached to the patient's legs prior to insertion of the delivery device 10 into the patient's body.

The sensor pack 52 is connected to an enunciator 56 shown, schematically, as a computer. The enunciator 56 generates a discernible alarm when the sensors 54 detect nerve stimulation. For example, the enunciator 56 may generate an audible and/or visual alarm signal.

In use, the closure element 18, which may be in the form of a sleeve axially or rotatably arranged relative to the introducer element 12, is moved to a position in which it occludes the opening 16. An incision is made in the patient's body and the introducer element 12 is introduced through the incision. When the tip 14 approaches the spine 58 (FIG. 10) of the patient, the tip 14 is energised to evoke a response from surrounding nerves as the delivery device 10 passes the nerves. In so doing, a clinician is able to inhibit the likelihood of damage being caused to the nerves.

The tip 14 is used to pierce the annulus 24 of the disc 22 to create an opening 60 (FIGS. 2 and 8) in the annulus 24. However, due to the fact that the annulus 24 is of criss-crossed collagen fibres, the applicant is of the view that, rather than breaking the collagen fibres, the fibres will be pushed apart allowing the distal portion of the introducer element 12 to penetrate into the cavity 28 of the disc 22.

When the distal portion of the introducer element 12 is within the cavity 28 of the disc 22, the closure member 18 is manipulated relative to the introducer 12 to open the opening 60. The nucleotomy wire 32 is extended into its bowed configuration (as shown in FIG. 8 of the drawings) in the manner described above. The introducer element 12 is rotated and reciprocated relative to the disc 22 so that the nucleotomy wire 32 dislodges nuclear material within the cavity 28 of the disc 22.

Further, as described above, if necessary, the nucleotomy wire 32 is energised with RF energy to aid in dislodging of nuclear material 30. A suction is applied to the lumen 41 of the introducer element 12 to aid in withdrawal of the nuclear material 30 from the cavity 28 of the disc 22.

Once nuclear material 30 has been removed from the cavity 28 of the disc 22, the nucleotomy wire 32 is withdrawn by unscrewing the control member 34 from the boss 36.

A proximal end of the filler tube 42 is attached to the source of filler material. Prior to the filler material being charged into the interior of the envelope, the filler tube 42 is connected, via a connection 62 (FIG. 2), near its proximal end, to a withdrawal device such as, for example, a syringe. Fluid in the form of air is withdrawn from an interior of the envelope 20 and the filler tube 42 causing both to collapse. Filler material is charged into the interior of the envelope 20 to cause the envelope 20 to be deployed laterally relative to the introducer element 12 through the opening 16, as shown schematically in FIG. 9 of the drawings. Due to the fact that the envelope 20 and filler tube 42 had previously been purged of air, formation of air bubbles in the prosthesis 44 is inhibited.

The envelope 20 is of an elastically deformable material, more particularly, a silicone material. Those skilled in the art will appreciate that the silicone material can expand to one hundred times its unstretched, or relaxed, configuration without plastically deforming. Thus, the filler material, which is also of a silicone material, is charged into the interior of the envelope 20 so that the material over-inflates the envelope 20. This causes distraction of the vertebrae and also allows the envelope 20 to conform to the shape of the cavity 28 once the introducer element 12 has been removed.

The filler material charging into the interior of the envelope 20 causes the envelope 20 to be dislodged from the distal end of the filler tube 42 once the envelope 20 is full. Instead, by appropriate manipulation of the introducer element 12, for example, by rotation, the filled envelope 20 can be detached from the filler tube and accordingly, the delivery device 10.

Regardless of the manner of detachment, once the envelope 20 has been detached from the delivery device 10, the delivery device 10 is removed from the opening 60 in the annulus 24 of the disc 22. As a result of the envelope 20 having been previously over-inflated, removal of the distal portion of the delivery device 10 from within the interior of the disc 22 allows the envelope 20 to conform to the shape of the cavity 28.

It is an advantage of the invention that a self-contained delivery device 10 is provided which can be used both to perform a nucleotomy of a disc 22 as well as to locate a tissue prosthesis 44 within the disc 22. Further, the use of a conductive tip 14 on the delivery device 10 reduces the likelihood of nerve damage when the procedure is carried out.

Still further, the delivery device 10 lends itself to performing such a procedure in a minimally invasive manner and with minimum trauma and discomfort being caused to the patient. It is to be noted that, in general, the stability of a nucleus prosthesis within the annular envelope is dependent on the integrity of the annulus at the time of implantation of the nucleus prosthesis. The annulus may have tears prior to implantation of the prosthesis. However, the size of the annulotomy performed to implant the nucleus prosthesis governs the possibility of extrusion of the prosthesis through the aperture resulting from the annulotomy. Using a finite element analysis model of the intervertebral disc, the applicants have demonstrated that, for an annulotomy aperture of less than 2 mm diameter, the likelihood of extrusion is significantly lower whilst, with a 5 mm diameter annulotomy aperture, the likelihood of extrusion or dislodgement of the prosthesis is greater. The device 10 displaces the fibres of the annulus rather than cutting them (core cut) and this is less likely to cause extrusion as the displaced fibres will tend to assume their initial position on removal of the device 10. Thus, due to the small diameter of the device 10 and the fact that the device 10 tends to displace the fibres of the annulus rather than cutting through them, the likelihood of extrusion of the implanted nucleus prosthesis is reduced.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. 

1. A tissue prosthesis delivery device which includes an elongate, tubular introducer element, the element having a tissue piercing distal end with an opening arranged proximally of the distal end; a closure member associated with the introducer element for opening and closing the opening of the introducer element; and an expansible prosthesis envelope received in a collapsed configuration within the tubular introducer element to be deployed laterally of the introducer element through the opening.
 2. The device of claim 1 which includes a tissue removal mechanism carried in the introducer element to be extended through the opening to aid in tissue removal at a site in the patient's body where the prosthesis is to be implanted.
 3. The device of claim 2 in which the tissue removal mechanism includes a filamentary element which is extended from the opening to effect tissue removal.
 4. The device of claim 3 in which the filamentary element is extended in a bowed configuration from the opening.
 5. The device of claim 2 in which the tissue removal mechanism is conductive to be energised to effect tissue removal.
 6. The device of claim 2 which includes a control member for controlling operation of the tissue removal mechanism.
 7. The device of claim 6 in which the control member is removably mounted to a proximal end of the introducer element, the tissue removal mechanism being removable for allowing deployment of the prosthesis envelope.
 8. The device of claim 1 in which the envelope is an elastically deformable envelope.
 9. The device of claim 1 in which the envelope is of an elastomeric material.
 10. The device of claim 1 in which at least the distal end of the introducer element is conductive to stimulate surrounding nerves in the patient's body electrically to evoke a response to reduce the likelihood of causing nerve damage as the introducer element is manoeuvred through the patient's body.
 11. The device of claim 1 in which the closure member is a sleeve displaceably arranged relative to the introducer element.
 12. The device of claim 1 which includes a filler tube in the introducer element with the envelope being mounted on a distal end of the filler tube and a proximal end of the filler tube being connectable to a supply of filler material.
 13. The device of claim 1 which includes a connection to a withdrawal device for withdrawing fluid from the envelope.
 14. A tissue prosthesis delivery device which includes an elongate, tubular introducer element, the element having a tissue piercing distal end with an opening arranged proximally of the distal end; a closure member associated with the introducer element for opening and closing the opening of the introducer element; and a tissue removal mechanism carried in the introducer element to be extended through the opening to aid in tissue removal at a site in the patient's body where the prosthesis is to be implanted.
 15. A tissue prosthesis delivery device which includes an elongate, tubular introducer element, the element having a tissue piercing distal end with an opening arranged proximally of the distal end; a closure member associated with the introducer element for opening and closing the opening of the introducer element; and at least the distal end of the introducer element being conductive to stimulate surrounding nerves in the patient's body electrically to evoke a response to reduce the likelihood of causing nerve damage as the introducer element is manoeuvred through the patient's body.
 16. A system for implanting a tissue prosthesis, the system including a tissue prosthesis delivery device as claimed in claim 10; a sensor pack attachable to the patient's body for sensing a response from any stimulated nerves; and an enunciator for alerting a clinician to a stimulated nerve.
 17. The system of claim 16 in which the sensor pack includes a plurality of sensors, each of which is attachable at a predetermined location on the patient's body.
 18. The system of claim 16 in which the enunciator includes an electromyograph (EMG).
 19. A method of implanting a tissue prosthesis, the method comprising minimally invasively introducing an introducer element into a patient's body using a tissue piercing distal end of the introducer element and the introducer element being tubular and carrying an expansible prosthesis envelope in a collapsed state within the introducer element proximally of the distal end; at a site in the patient's body at which the prosthesis is to be formed, deploying the envelope through an opening defined, proximally of the distal end, in a side wall of the introducer element by charging a filler material into an interior of the envelope to cause the envelope to expand and conform to a cavity at the site in the patient's body; and detaching the expanded envelope from the introducer element and withdrawing the introducer element.
 20. The method of claim 19 which includes energising at least the distal end of the introducer element to evoke a response from surrounding nerves of the patient as the introducer is manoeuvred to the site to inhibit damage to the nerves.
 21. The method of claim 19 which includes, initially, removing tissue from the site using the introducer element.
 22. The method of claim 21 in which the introducer element includes a tissue removal mechanism and in which the method includes extending the tissue removal mechanism through the opening of the introducer element and manipulating the introducer element to facilitate removal of tissue from the site by the tissue removal mechanism.
 23. The method of claim 22 which includes energising the tissue removal mechanism to aid in tissue removal.
 24. The method of claim 22 which includes, after tissue removal has been completed, removing the tissue removal mechanism from the introducer element to allow the prosthesis envelope to be expanded through the opening of the introducer element.
 25. The method of claim 19 in which the opening is closed by a closure member and in which the method includes displacing the closure element relative to the introducer element when the introducer element is in the desired position relative to the site to place the interior of the introducer element in communication with the site.
 26. The method of claim 19 which includes expanding the envelope to a size greater than a cavity which the envelope is to fill so that, upon removal of the introducer element after filling of the envelope, the envelope conforms to the size of the cavity. 